Which medications are used in the treatment of male breast cancer?

Updated: Feb 11, 2021
  • Author: Bagi RP Jana, MD, MBA, MHA, FACP; Chief Editor: John V Kiluk, MD, FACS  more...
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Answer

Recommendations for use of systemic therapy in male breast cancer are generally the same as in female breast cancer, because the rarity of male breast cancer has precluded the performance of clinical studies. Tamoxifen is the recommended adjuvant endocrine therapy. Duration is at least 5 years and in appropriate patients can be extended to 10 years, given the results of the Adjuvant Tamoxifen: Longer Against Shorter (ATLAS) trial. [11]  

American Society of Clinical Oncology (ASCO) guidelines recommend offering tamoxifen to men with hormone receptor–positive breast cancer who are candidates for adjuvant endocrine therapy. The initial treatment duration is 5 years; men who have completed 5 years of tamoxifen, have tolerated therapy, and still have a high risk of recurrence may be offered an additional 5 years of tamoxifen therapy. [12]

Data are limited regarding the use of aromatase inhibitors in men. A retrospective study indicates that aromatase inhibitors may be associated with poorer outcomes in men when compared with tamoxifen. The overall survival (OS) of tamoxifen-treated female and male patients had similar 5-year OS, 85.1 and 89.2%, respectively (P = 0.972). Notably, in patients treated with an aromatase inhibitor, 5-year OS was significantly greater in females than in males (85.0% versus 73.3%; P = 0.028). [13, 14]

ASCO guidelines recommend that men with hormone receptor–positive breast cancer who are candidates for adjuvant endocrine therapy but have a contraindication to tamoxifen may be offered a gonadotropin-releasing hormone (GnRH) agonist/antagonist and an aromatase inhibitor. [12] National Comprehensive Cancer Network (NCCN) guidelines also advise that when an aromatase inhibitor is used in men, a GnRH analog should be given concurrently. [15]  

In addition, NCCN guidelines note that available data suggest single-agent fulvestrant has similar efficacy in men as in women. Although newer agents such as CDK4/6 inhibitors (in combination with an aromatase inhibitor or fulvestrant), mTOR inhibitors, and PIK3CA inhibitors have not been systematically evaluated in clinical trials in men with breast cancer, the NCCN considers it reasonable to recommend these agents to men with advanced breast cancer, based on extrapolation of data from studies comprised largely of women. Use of chemotherapy, HER2-targeted therapy, immunotherapy, and PARP inhibitors for advanced breast cancer mirrors the use of those agents in women. [15]

ASCO guidelines recommend that men with advanced or metastatic, hormone receptor–positive, HER2-negative breast cancer should be offered endocrine therapy as first-line therapy, except in cases of visceral crisis or rapidly progressive disease. Options include tamoxifen, an aromatase inhibitor plus a GnRH agent, and fulvestrant. CDK4/6 inhibitors can be used in men as they are used in women. Those men who exprience a recurrence of metastatic, hormone receptor–positive, HER2-negative breast cancer while receiving adjuvant endocrine therapy should be offered an alternate endocrine therapy, except in cases of visceral crisis or rapidly progressive disease. [12]

ASCO guidelines also recommend that targeted therapy guided by HER2, PDL-1, PIK3CA, and germline BRCA mutation status may be used in the treatment of advanced or metastatic male breast cancer, using the same indications and combinations that are offered to women. Management of endocrine therapy toxicity is similar to the approach used for women. [12]

Palbociclib, a cyclin-dependent kinases (CDK) inhibitor, gained FDA approval in 2109 for treatment of men with breast cancer. It is indicated for treatment of adults with hormone receptor–positive/HER2-negative advanced or metastatic breast cancer in combination with an aromatase inhibitor as initial endocrine-based therapy in men or postmenopausal women, or in combination with fulvestrant in patients with disease progression following endocrine therapy. For men treated with combination palbociclib plus aromatase inhibitor therapy, consider treatment with a luteinizing hormone–releasing hormone (LHRH) agonist. [15, 16]

Most cases of metastatic male breast cancer are estrogen receptor (ER)–positive, and guidelines from the European School of Oncology and the European Society for Medical Oncology recommend endocrine treatment with tamoxifen as the preferred option for these patients, unless they have suspected or proven endocrine resistance or rapidly progressive disease that requires a fast response. [17]  Second-line hormonal approaches include orchiectomy, aromatase inhibitors, and androgen ablation. [18] However, chemotherapy can also provide palliation.


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